Grinding machine



May 30, 1933. FRASER 1,911,890

GRINDING MACHINE Filed March 14, 1929 3 Sheets-Sheet l 15' 6 Fig. 2

I gwuwntoz WITNESSES 7 WARREN F. FHHSEfi W H. M I W W W.

May 30, 1933.

w. F. FRASER GRINDING MACHINE Filed March 14, 1929 3 Sheets -Sheet Fig.4

Fig. 5

gwuewtoo I MRREN I-T FFrHSER WITNESSES Patented May 30, W33

WARREN F. FRASER, 0F WESTBORO; MASSACHUSETTS, ASSIGNOB- T0 NOETON COMP 40F WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS GRINDINGMACHINE Application filed March 14, 1929. Serial No. 347,097.

This invention relates to feeding mechanism for machine tools wherein itis desirable to efiect a relative movement of the work and an operatingtool at different rates of speed and with extreme accuracy. Whilevcertain features of the invention are of general application, it is ofparticular value as embodied in grinding machines wherein the Work andthe grinding element are relative- 1y moved toward and away from eachother at different rates in diiferent parts of the machine cycle,Accordingly, the invention will be first disclosed in its application togrinding machines.

Fluid pressure systems have been employed heretofore in connection withthe feeding mechanism of grinding machines and such systems aredesirable on account of their smooth and continuous action and thesimplicity of their mechanical construction. In one aspect, the presentinvention consists broadly in feeding mechanism including a fluidpressure actuator, a controlling valve for governing the action thereof,and a caliper device operating on the work during the grinding operationto which the controlling valve is responsive.

It is important, to insure the accurate operation of the caliperingdevice, that it should be light in construction and effective in itscontrolling action under conditions of light pressure. The area of itscontact points must be kept small in order to reduce the possibility offoreign matter being retained between them and the work and the pressuremust be light to avoid marking the work, especially where it is nothardened. In another aspect, the present invention consists incalipering mechanism of novel construction wherein the caliperingmovement is utilized to trip a sensitive latch mechanism underconditions of light pressure and the tripping of the latch mechanism istakenadvantage of in a novel manner to govern a controlling valve in thefluid pressure system. As herein shown, the controlling valve isarranged to be positioned initially by the operator and this operationenergizes a spring which is subsequently utilized to effectautomatically the movement of the valve when tripped by the caliperingdevice. By this construction I have found it possible to maintainadequate flow of fluid under pressure during the grinding operation andyet elfectually cut oft" the flow in response to an extremely slight anddelicate movement of the caliper elements.

Other features of the invention relate to novel feeding mechanism of thefluid pressure type, whereby the work and the grinding element may bemoved toward and from each other accurately, with adequate power and atspeeds appropriate to the difierent requirements. As herein shown, thegrindlng wheel is moved at high speed from a remote initial positioninto a preliminary grinding relation to the Work, then fed in to thework at a slow speed until a predetermined diameter is reached, thenheld at rest While a final reduction of diameter is edected, and finallyretracted at high speed to its initial position.

To accomplish these results, the present invention contemplates feedingmechanism actuated by fluid pressure and a separate fluid pressuresystem for controlling the rate of feed. It is believed that theprinciple which this combination of fluid pressure systems involves hasnot been heretofore employed in controlling the feeding mechanism ofgrinding machines or other machine tools. It presents the advantages ofsmoothness of operation without shock or overthrow, reliability, and awide range of variation as to rate of feed. As herein shown, theseparate fluid pressure system referred to includes a passage throu hwhich fluid under pressure is forced during the in-feeding operation,which passage is provided with an adjusting valve for varying itsefiective opening and thus controlling the rate of fluid displacementand, consequently, of the feeding movement. The system also includesmechanism by which it is brought into action at a predetermined point inthe feed so that, if desired, the initial feeding movement to establishthe grinding relation may take'place at a higher rate of speedindependent of the control of the system.

These and other features of the invention will be best understood andappreciated from the following description of a preferred embodimentthereof, selected for purposes of illustration and shown in theaccompanying drawings, in which Fig. 1 isa view in perspective showingsomewhat diagrammatically the arrangement of the grinding wheel slideand its feedmg mechan1sm, the work and the calipering device;

Fig. 2 is a sectional view of the calipering device on the line 22 ofFig. 8;

Fig. 3 is a sectional view, on the line 33 of Fig. 5, of the hand wheeland associated parts;

Fig. 4 is a sectional view of a portion of the calipering device on theline 44 of Fig. 7;

Fig. 5 is a view in elevation, partly in section, of the feedingmechanism Fig. 6 is a plan view of the calipering device;

Fig. 7 is a view in end elevation of the controlling valve mechanism,partly in section; and

Fig. 8 is a view in elevation of the calipering device with itsassociated mechanism shown in section.

In the cylindrical grinding machine illustrated, the grinding wheel 100is mounted on a driven shaft 102 journaled in a cross slide 104 suitablysupported and guided by transverse ways in the machine frame. In thebottom of the grinding wheel slide 104 'is a nut 106 which cooperateswith the lead screw in a transverse shaft 12 for movin the slide tocarry the grinding wheel toward or from the work. The work piece to beground is illustrated as a shaft 108 supported upon centers, one ofwhich110 is shown in Fig. 1, and arranged to be rotated while beingground. The mechanism thus far described is well known in commercialgrinding machines such, for example, as that shown in the patent toNorton No. 1,443,924, grant-- ed Jan. 30, 1923.

To move the grinding wheel 100 toward and from the rotating work, thefollowing mechanism is employed. The lead screw shaft 12 carries apinion 27 at its forward end which meshes with another pinion 28 on therear end of a shaft 10 journaled in the machine frame. Rotation istransmitted to the lead screw shaft 12 through the shaft 10, which maybe turned manually by a hand wheel 14 fast to its forward end ormechanically and automatically through a pinion 13 which, in turn, isdriven by a reciprocatory rack 26. The pinion 13 may be locked to theshaft 10 or may be free to rotate upon it according as it is desired toutilize the automatic feed or the manual feed. To thisend, a gear 15 issecured to the pinion 13, being arranged to turn with it upon the shaft10 and to mesh with a pinion 24 formed in the.

rear end of a plunger 21 which is slidably mounted in a sleeve 16. Thesleeve 16 is slidably keyed to plunger 21 and free to turn with it inthe hand wheel 14. It has a radially extending arm carrying a lockingpin 17 adapted to enter one of a series of holes 20 arrangedcircumferentially in a disk secured to the hand wheel 14 and beingmaintained in locking position by a spring, shown in Fig. 3. The plunger21 may be retracted, disengaging the pinion 24 from the gear 15, when itis desired to free the hand wheel 14 and the shaft 10 from the automaticfeed mechanism.

It is desirable, for purposes which will presently appear, to providefor changing by small amounts the angular relation of the pinion 13 andthe shaft 10 and this may be effected by rotating the sleeve 16 and theplunger 21 through the desired angle and looking it in adjustedposition, as determined by one or another of the holes 20.

Provision is made for moving the rack 26 at two different speeds in adirection to advance the grinding wheel toward the work and at one speedin the reverse direction. To this end, the rack 26 is provided at eitherend with downwardly extendir 1g arms 28 and 30 between which extends apiston rod 32. The rod 32 passes through the heads of a fluid pressurecylinder 36 and is provided with a piston 34 by which it is moved ineither direction according to which end of the cylinder fluid pressuremay be admitted. A pipe 62, connected to the left head of the cylinder,acts as an inlet pipe during the in-feeding movement of the grindingwheel and a pipe 64, connected to the right head of the cylinder, actsas anoutlet pipe at the same time. The functions of these pipes areinterchanged during the reverse movement of the grinding wheel.

During a portion of the in-feeding movement of the grinding wheel, therack 26 travels at high speed without retardation, bringing the grindingwheel from a remote position up to a position closely adjacent to or inpreliminary engagement with the work to be ground. When this conditionhas been reached, further movement in the same direction is continuedbut at a greatly reduced speed and such motion constitutes the grindingfeed. To effect this result, the motion of the rack 26 is retarded. Tothis end, an auxiliary cylinder 40 is arranged beneath and parallel tothe cylinder 36'and is provided with a piston 42 connected to a pistonrod 44 extending through the left-hand head of the cylinder 40 andadapted to be engaged at a predetermined point in the travel of the rack26 by the lower end of the arm 30 which is secured to the rack. Thecylinder 40 is normally filled with oil or other fluid and the pistonrod is normally moved outwardly toward the left by a compression spring46 which encircles the piston rod 44 and bears between the collar 45,fast to the piston rod, and the head of the cylinder. The right-handhead 38 of the cylinder is provided with an outlet port communicatingwith a valve member 50 having an outlet passage controlled in size by aneedle valve 52 and a by-pass normally closed by a check valve 54. 0thpassages communicate with a pipe 56 leading to an oil reservoir 58arranged somewhat above the level or the cylinder 40. It will beunderstood that the high speed movement of the rack 26 toward the right(Figs. 1 and 5) is terminated when the arm engages the end of the pistonrod 44. Further movement of the rack 26 is effected against theresistance of the oil confined between the piston 42 and the smalladjustable outlet controlled by the needle valve 52. Only as oil escapesthrough this passage can the piston 42 move and the rate of I travel ofthe rack 26 is, accordingly, reduced to the speed determined by thesetting of the needle valve.

When the grinding feed movement and the final grinding have both beencompleted and the piston 34 is moved toward the left by reversing thedirection of fluid pressure within the cylinder 36, as will be presntlyexplained, the spring 46 is efiective to move the piston 42 toward theleft and the check valve 54 will open, permitting the oil which has beendisplaced at a slow rate to the reservoir 58 now to return rapidly andfollow the piston 42.

The mechanism for controlling the admission of fluid pressure to thecylinder 36 will now be described. In certain phases this is controlledby the action of a caliper device, shown in Figs. 2 and 8/ Ways 130 areprovided in the machine frame for supporting the caliper device, whichis mounted upon a bracket 132 shaped to fit the ways and to be clampedin any desired position thereon by a clamping plate 134 which is boltedto the lower side of the bracket. The bracket 132 has a plane upper faceand a carrier member 136' pivotally mounted at its lower end upon a pin138. Pivotally mounted by a pin 139 in the upper end of the carriermember is a frame piece 140 which carries two forwardly extending bars142 and 144. The bar 144 is provided with a boss in which is mounted aspring plunger 146 which bears upon the plane upper face of the bracket132 and urges the bars 142 and 144 and the parts carried therebyupwardly to a position determined by the-engagement of the lower calipermember with the bottom of the work. The plunger 146 is provided at itsupper end with a stop nut which serves to limit the downward movement ofthe plunger and, consequently, the upward movement of the caliper barswhen no work is engaged by the lower caliper member. The bars 142 and144 are riveted together by rivets 148 and these extend through theupper end of a downwardly curved bracket member 150. A horizontallydisposed stop screw 152 projects through the bracket member 150 and isarranged to engage the work piece at a point substantially opposite thegrinding point and to locate transversely the calipering device. .Thebracket member also carries at its lower end an upwardly extendingcontact screw 156 which is designed to engage the bottom of the workpiece, being pressed against it by the action of the spring plunger 146.

Between the bars 142 and 144 and above the bracket member 150 ispivotally mounted a rocker bar 160 upon a transverse pin 162. At itsforward end the rocker bar carries a contact screw 164 arranged toengage the upper side of the work piece. The pin 162 .is provided withflanged bushings and surrounded by a sleeve 17 O in itsenlar gedintermediate portion. The sleeve ,170 has an opening through whichpasses the lower end of a locking pin 172 threaded .into the rocker bar160 and adapted to engage a fiat formed in the pin 162 and to retain itagainst endwise displacement.

Journalled on the sleeve 170 and flush with the sides of the rocker bar.160 is a forked beam 180, the two branches of which are shown in sectionin Fig. 2. In the rear end of the rocker bar 160 is provided anadjusting screw 184 which is adapted to bear at its lower end upon atransverse web 182 in the forked beam 180. The adjusting screw isprovided with a graduated knurled head cooperating with a spring detcntto maintain the screw in all positions of adjustment. The

rocker bar 160 and the forked beam 180 constitute in sheet a singletwo-part rocker, the arms of which may be relatively adjusted by turningthe adjusting screw 184. A hairpin spring 188, located between the forksof the beam 180, serves to maintain the end of the adjusting screw 184always in engagement with the web 182. A leaf spring190, mounted betweenthe bars 142 and 144 and bearing upon the web 182 near its lower end,serves to counterbalance the compound beam and maintain the contactscrew164 in engagement with the upper surface of the work piece. By turninthe adjusting screw 184 downwardly, the rorward end of the rocker bar160 is lowered and contact screw 164 brought closer to the contact screw156, thus aflording convenient means for making an adjustment fordetermining the point at which the caliper acts in controlling thegrinding.

The fluid pressure controlling valves, which are controlled by the beam180 as its outer end moves upwardly, will now be described. The rear endof'the beam 180, which is periorated for the sake of lightness, extendsinto a housing 191 where it is provided with a transverse extension 192'at either side carrying an adjustable contact screw 194. Each contactscrew 194 is arranged in vertical alignment with and beneath a trippingpawl 196 pivotally mounted in the casing 191. and cooperating'at itsfree end with a single tooth ratchet disk 198 fast on a transverse shaft200 journaled in the casing and carrying a pinion 204 at its outer end,see Fig. 4. Each pinion 204 meshes with a gear 206 on a transverse shaftjournaled at the rear of the shaft 200 and having an elongated pinion208. Each pinion 208 meshes with a rack formed in a vertically disposedrod 210 and each rod extends upwardly through the cover of the casing,where it is provided with a knob by which it may be moved manually inone direction, that is to say, downwardly.

Beneath the casing 191 and secured to the frame piece 140 is a valveblock or body 212 having two vertical cylindrical bores therein toreceive ground sleeves 214, each constituting a valve cylinder. Thelower end of each valve cylinder 214 is closed by a head 220 and a valveplunger 216 is arranged for vertical movement within each cylinder. A.compression spring 218 interposed between the bottom of the valveplunger and the head 220 tends to move the valve plunger at all timesupwardly into the dotted line position shown in Fig. 7. Each valvelunger 216 is eirtended through the upper ead' of its cylinder andengages with the lower end of one of the rods 210 by which it may bemanually depressed against the action ofthe spring 218.

Each valve plunger has a centrally disposed reduced portion and twoheads which fill the bore of its cylinder. Fluid pressure is supplied tothe inlet port 222 of the lefthandvalve by an inlet pipe whichmay extendto any source of fluid pressure, such as an air compressor oraccumulator. en the valves occupy the position shown in Fig. 7, whichthey do when they have been manually depressed, fiuid under pressurepasses through the left-hand valve to the port 224 and thence to thepipe 62 with which it communicates. The piston 34 in the cylinder 36,therefore, travels toward the right and fluid under pressure isexhausted, through the pipe 64 communicating with the port 226 of theright-hand valve and from thence, through the valve, to the exhaust port228, where it escapes 'to the atmosphere.

The valves remain in position shown in Fig. 7 during the preliminaryin-feeding movement of the grinding wheel and during the slow grindingfeed thereof. The termination of the grinding feed is determined by theaction of the caliper device when the work has been reduced to apredetermined diameter that will permit the left-hand pawl 196 to betripped from the ratchet tooth of the disk 198. When this occurs, thelefthand valve is immediately moved to the dotted line position, shownin Fig. 7 and the inlet'port 222 is closed, holding the piston34stationary and maintaining the grinding wheel at rest. The grindingoperation continues under these conditions until all strains it i themechanism have been dissipated and the resulting slight furtherreduction in the diameter of the work has occurred. When this point isreached, the slight additional movement imparted to the beam 180 issulficient to release the right-hand pawl 196, permitting the right-handcontrolling valve to move to the dotted line position shown in Fig. 7.Under these conditions fluid under pressure supplied by the pipe 60passes through the internal passage 230 which extends in the valve bodybetween the port 222 and a port 232 of the right-hand controlling valve.From this port fluid pressure enters the right-hand valve and reachesthe port 226, whence it passes to the pipe 64 and is admitted to theright end of the cylinder 36, forcing the plunger 34 toward the left andmoving the grinding wheel rapidly away from the work. During this partof the cycle, fluid under pressure is exhausted from the cylinder 36through the pipe 62 and reaches the left-hand valve through the port224, from whence it passes through the valve andescapes to theatmosphere through the outlet port 225. Vent ports 227 and 228 areprovided at the upper endof the lefthand and right-hand controllingvalves respectively to prevent air from being entrapped therein. Y

It will be understood that the caliper device has a double pivotmounting which permits it to move freely up and down and toward and fromthe work, the pivots being the in 138 and the pin 139 which connects therame piece 140 with the carrier member. 1

A lever 250 is provided for convenience in manually shifting the caliperdevice into and out of operative position. The pin 139 is extended outthrough the frame piece 140 and forms a fulcrum for the lever 250. Alink 301 is pivotally connected at one end to the lever 250 by a bolt.The opposite end of the link is slotted, as shown in Fig. 1, and adaptedto engage the reduced outer end of a stud set rigidly in the bracket132. A tension spring normally maintains thisstud in contact with theinner end of the link 301. The portion of the lever 250 adjacent to itsfulcrum and the link 301 constitute a toggle mechanism which, in theposition shown, is locked; that is, its pivot point lies below the lineof the link 301.

lVhen the lever 250 is moved upwardly about its fulcrum point, thetoggle is broken and the entire caliper device is moved to aninoperative position away from the work. When the lever 250 is swung inthe other direction, the caliper device is moved to operative engagementwith the work as determined by its three contact screws. The caliemeeoThe operation of the feeding mechanism in screws 156 and 164 intoengagement with the spring connection with the grinding machine abovedescribed is as follows. Appropriate preliminary settings are first madein respect to the position of the pinion 13 with reference to the feedshaft 10 to bring the grinding wheel into the desired initial relationto the work piece- 108. The caliper device is moved into operativeposition opposite the grinding wheel 100 and a preliminary setting ismade by turning the contact screws to bring the work at diametricallyopposite points and the rocker bar 180 into a position to permit the twodisks to be locked by the pawls 196 when the valves 216 are depressed bythe operator. When this occurs, the valves occupy the positions shown inFig. 7, the inlet port 222 being open and fluid under pressure beingadmitted to the cylinder 36 at its lefthand end. The piston 34 and therack 26 are, therefore, moved rapidly toward the right and the shaft 10rotated in a direction to feed the grinding wheel rapidly toward thework. The rapid in-feeding movement is of measured duration andterminates when the arm 30 encounters the end of the contact rod 44, asit is about to do with the parts in the position shown in Fig. 5.

The high speed in-feeding movement is a movement preliminary to theactual grinding and brings the grinding wheel in from the inoperativeinitial position which it 00- cupies during the insertion of the work toa position in which it is barely in grinding contact with the work. Atthis point the arm 30' begins to displace the rod 44 and piston 42toward the right against the tension of the 46 and against the backpressure of the 011 contained in the cylinder 40. Since 3 the fluidpressure against "the piston 34 remains constant, the increasedresistance made effective b the piston 42 abruptly reduces the rate ofmovement of the rack 26 so that the in-feeding movement of the grindingwheel continues at a greatly reduced rate. The oil behind the piston 42is forced outwardly at a rate determined by the setting of the needlevalve 52 and is delivered to the reservoir 58. The 'in-feeding movementcontinues under these conditions until the caliper device permits thebeam 180 to rise sufficiently to trip the left-hand pawl 196 from itsassociated disk. thereby releasing the lefthand valve 216 and permittingit to move up- 0 wardly' to the position indicated in dotted ing wheelmaintained in the position thus determined by the action of the caliper,while a further slight reduction in the diameter of the work is efiectedwhile the machine strains are dissipated and pressure of the grindingwheel against the work relieved. The adjustable contact-screw 194 in theright-hand side of the extension 192 of the beam 180 is set so that themovement of the caliper in response to this final grinding will trip theright-hand pawl 196 and release the righthand valve 216, permitting itto move upwardly and establish communication between the ports 232 and226 so that fluid under pressure is now admitted to the right-hand endof the cylinder 36 and the rack 26 is moved in the direction to rotatethe shaft 10 for'the reverse feeding movement. This movement takes placeat high speed and independently of the separate rate-controlling fluidpressure system because the arm 30 at once moves away from the contactrod 44. As already explained, the piston 42 is returned to initialposition by the spring 46, the check valve 54 opening to'permit thefluid from the reservoir 58 to follow the piston. The operator may nowrelease the caliper device from the finished work and insert a new pieceof work in readiness for a repetition of the operations just outlined.

It will be noted that the in-feeding movement of the grinding wheel iscaused by the setting of the controlling valves 216 by the hand of theoperator. The stopping of the grinding feed and the separating of thewheel and the work, on the other hand, are efl'ected by the movement ofthe valves occurring automatically in accordance with the action of thecaliper device. In case it should be desired to rough grind a work pieceindependently of the caliper device, the operator may depress the rods210 without positioning the caliper upon the work. This movement of thevalves will start the rapid approaching movement of the grinding wheelwhich will, at the proper time, automatically shift as above describedto the slow in-feed and when the wheel has ground away the rough outersurface of the work, the operator may swing the caliper device forwardinto operative engagement and leave the valves to their automaticcontrol.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. In a inding machine having a work support an a rotatable grindingwheel, feeding mechanism for the wheel, a fluid pressure cylinder andpiston for actuating the mechanism in either direction, a controllingvalve, actuating mechanism therefor arranged to be latched under springtension in a position to admit fluid under pressure to the cylinder tocause an infeed of said mechanism and to cut off fluid when released tostop said infeed, and a caliper device having members engaging the workat diametrically opposite points for tripping said valve actuatingmechanism.

2. In a grinding machine, feeding mechanism, a fluid pressure cylinderand piston for actuating said mechanism in either direction, acontrolling valve therefor which is biased to a closed position, a geartrain operatively connected to move with said valve, means to lock saidtrain to hold the valve in an open position to cause an infeed of saidmechanism, a trip acting to release said means to cut off fluid to stopsaid infeed, and a caliper device engageable with the work andoperatively connected to actuate said trip and stop the feedingmovement.

3. In a grinding machine, feeding mechanism, a fluid pressure cylinderand piston for actuating said mechanism, a valve for controlling theadmission of fluid pressure to said cylinder and its cut-ofl therefrom,a spring tending to move said valve to its cut-off position, a geartrain connected to the valve and including a ratchet disk, a'pawlcooperating with said disk .to latch the gear train with the valve inpressure-admitting position, and a caliper device arranged to trip saidpawl.

4. In a grinding machine, feeding mechanism, a fluid pressure cylinderand piston for actuating said mechanism, a pair of valves arranged sideby side and movable successively to effect a stopping of fluid pressureand a reversal of the direction of pressure in the cylinder, and acaliper device acting to initiate the movement of said valves one afterthe other.

5. In a grinding machine, feeding mechanism, a fluid pressure cylinderand piston for actuating said mechanism, a pair of valves forcontrolling the admission of fluid pressure to opposite ends of thecylinder, means independent of said valves for regulating the rate offeed in one direction, and a caliper device to which said valves aresuccessively responsive.

6. In a grinding machine, a grinding wheel slide, a feeding mechanismtherefor including a nut and screw connected to move the slide, a fluidpressure system including a piston connected to rotate the feed screw inopposite directions, a stop connected to said piston, and a separatefluid pressure system including a dash pot having a piston arranged inthe path of said stop to establish a back pressure and produce a slowfeed of the wheel, means for adjustably regulating the effective backpressure in said separate system, and means for effecting the reversemovement of said dash pot piston independently of the feeding mechanism.

7. In a grinding machine, feeding mechanism, a fluid pressure cylinderand piston, a

rack reciprocated thereby for operating the feeding mechanism, a stopcarried by the arranged to be latched under tension by the operator tohold said valve open, and a trip actuated by said calipering device torelease the latch so that the valve will close and stop the feedingmovement when the work reaches a predetermined size.

9. A grinding machine having a base, a work support, a transverselymovable wheel slide, a rotatable grinding wheel on said slide, a feedmechanism including a nut and screw to move the slide and wheel towardsand from the work, a fluid pressure device to rotate said feed screw andfeed the wheel continuously into the work, and a caliper mechanismarranged to engage the work piece and to control said fluid pressuremechanism and wheel feed to stop the feed when the work reaches apredetermined size.

10. In a grinding machine having a base, a work support, a transverselymovable wheel slide, a rotatable grinding wheel on said slide, a feedmechanism to move the slide and wheel towards and from the work, a fluidpressure device to actuate said feed mechanism, a calipering devicearranged to engage the work piece, and two valves responsive to movementof said calipering device which are arranged to successively stop theinfeed and to move the wheel rearwardly to an inoperative position.

11. A feeding mechanism for grinding machines having a work supportand'a rotatable wheel comprising a nut and screw mechanism to feed thegrinding wheel toward and from the work, a rack bar arranged to turnsaid feed screw in either direction, a fluid pressure piston andcylinder mechanism op-- eratively connected to move said rack in eitherdirection, a caliper arranged to engage the periphery of a work piece,and a valvemechanism actuated by said caliper to stop and reverse theflow of fluid and-thereby remove the wheel from the work when the workhas reached a predetermined size. I

12. A grinding machine having a base, a work support, a transverselymovable wheel slide, a rotatable grinding wheel on said slide, a feedmechanism including a feed screw and nut to move the slide and wheeltowards and from the work, means including a piston and cylindermechanism to rotate said feed screw and continuously feed the grinding.wheel rapidly into the work, and a calipering device including a valvewhich is arranged to be actuated when the work reaches a predeterminedsize to reverse the flow of fluid in the cylinder and remove thegrinding wheel from an operating position.

13. In a grinding machine having a rotatable grinding wheel and a worksupport, a feeding mechanism for said wheel, a fluid pressure cylinderand piston for actuating said mechanism, a pair of valves arrangedadjacent each other, one of said valves being movable to stop themovement of the feeding mechanism in one direction, the other valvebeing arranged for movement thereafter to reverse the direction of flowof said fluid pressure to reverse the feeding movement, and a caliperdevice actuated to initiate the movement of said valves one after theother.

14. A grinding machine comprising a work support and a grinding wheelwhich are relatively movable towards and from each other to effect agrinding operation, a feedin mechanism therefor, a calipering deviceliaving a member movable in response to a decrease in size of the work,a fluid pressure actuated mechanism including a cylinder and pistonoperatively connected to actuate said feed mechanism to cause a relativeinfeed and reverse movement of the Wheel and the work, and meansincluding a control valve responsive to movement of said caliper membereffective to control said fluid pressure mechanism and cause the infeedmovement to cease when the work has reached a predetermined size and areverse movement when the work has been ground to a final size.

15. A grinding machine comprisin a work support and a grinding wheel wich are relatively movable towards and from each other to effect agrinding operation, fluid pressure actuated mechanism including a valvecontrol device to cause a relative infeed and a reverse movement of thewheel and the work, a caliper device having a movable member engageablewith the work and means responsive to movement of the caliper memberwhich actuate the valve control device and cause the infeed movement tocease when the work has been ground to a predetermined size and areverse movement when the work has been reduced further to its finalsize.

16. A grinding machine comprising a work support, a grinding wheelmovable towards and from the work, a fluid pressure actuated mechanismto move the wheel forward for a grindin operation and rearwardly fromthe wor two valves for controlling said mechanism, one being connect--ed to stop the infeed of thecwheel and the other to cause the wheel tomove rearwardly, a caliper device including a member movable in responseto a decrease in size of the work and means responsive to movement ofsaid caliper member which is connected to actuate said valvessuccessively when the work reaches a predetermined finished size,

and means including a second valve controlled thereafter by said calipermechanism to move the grinding wheel rearwardly after ithas been groundto a predetermined size.

18. A grinding machine comprisin a work support and a grinding wheel, auid pressure actuated feed mechanism to move the wheel towards and fromthe work, a caliper engaging the work, two valve mechanisms controllingthe feed mechanism, one connected to stop the infeed of the wheel andthe other to cause the wheel to move rearwardly, an actuating mechanismfor each valve, and connections between said caliper and the valveactuating mechanisms which cause the latter to act successively.

19. A grinding machinehaving a base, a work support, a transverselymovable wheel slide, a rotatable grinding wheel on said slide, a feedmechanism to move the slide and wheel towards and from the work, meansincluding a piston and cylinder mechanism to actuate said feedingmechanism and feed the grinding wheel rapidly into the work, a secondarycylinder and piston arranged to serve as a dash-pot to slow down thefeeding movement of the grinding wheel when the grinding wheelapproaches the surface of the work, a valve in said secondary cylinderarranged to adjust the'slow feeding movement for the grinding wheel, anda calipering device including-a'valve which is arranged to be actuatedwhen the work reaches a predetermined size to reverse the flow of fluidin the cylinder and remove the grinding wheel from an operatingposition. 20. A grinding machine having a base, a

Work support, a transversely movable wheel,

slide, a rotatable grinding wheel on said slide, a rotatable feedmechanism to move the slide towards and from the work, a fluid pressuredevice including a piston and cylinder which are operatively connectedto move a rack bar to turn the feed mechanism and feed the grindingwheel rapidly towards the work, a secondary cylinder and piston arrangedto slow down the feeding movement of the grinding wheel at apredetermined point, a calipering device arranged to engage the workpiece, anda valve actuated by said caliper to reverse the flow of fluidto said first cylinder and move the wheel rearwardly when the work hasbeen ground to a predetermined size.

Signed at Worcester, Mass, this 13th day of March 1929.

WARREN F. FRASER.

